In recent years, in medical institutions and nursing facilities, there is a case where a watching system using a camera has been used to watch getting up, leaving bed, and behaviors of a patient, a cared person, or the like lying on a bed instead of medical welfare workers such as nurses or care workers. Such a watching system is used for the purpose of notifying abnormality instead of a patient or the like in a case where there occur behaviors such as getting up and leaving bed of the patient or the like leading to falling down or falling accident, or extraordinary situations in which the patient is suffering and unable to press a nurse call button.
In the watching system, a technique for extracting a bed area from an image is disclosed since a range of the bed area in the image is used as a reference when recognizing a behavior of a person on the bed from the image captured by the camera.
Japanese Laid-open Patent Publication No. 2012-71003 and Japanese Laid-open Patent Publication No. 2008-167931 are examples of the related art.